The present invention relates to personal wash cleanser compositions comprising an a-hydroxy benefit agent which in turn comprises mixtures of both short chain (C.sub.2 -C.sub.10) and long chain (C.sub.11 -C.sub.24) a-hydroxy acid esters. More specifically, by combining the longer term moisturizing effect of short chain esters, (note, short chain esters such as butyl (S)- or octyl (S)-lactate often have initial drying effect) with the shorter term moisturizing/masking benefit of long chain esters (e.g., octadecyl (S)-lactate), applicants have obtained superior compositions. Mixing both short and long term moisturizing effects allows compositions to be prepared which have long term beneficial effects while providing short term visual tactile effects of soft, smooth skin. More specifically, applicants have been able to mix short chain esters (normally drying) with long chain esters and significantly reduce the drying effect of the short chain esters while providing longer term moisturizing effects associated with the shorter chain esters.
The use of short chain .alpha.-hydroxy acid esters (e.g., C.sub.1 to C.sub.4 alkyl lactates to treat acne) or long chain .alpha.-hydroxy acid esters (e.g., long chain lactate ester emollient) is broadly taught in the art. No art, however, teaches a specific combination of long and short chain esters of .alpha.-hydroxy acid (e.g., lactic acid) or that, in combination, the long and short chain esters could provide multiple benefits.
U.S. Pat. No. 4,540,567 to Oneto et al. (assigned to Lever Brothers), for example, teaches compositions comprising short chain C.sub.1 -C.sub.4 alkyl lactate (primarily for treatment of acne) or mixtures which are dissolved in a mixture of water and water-miscible C.sub.2 -C.sub.4 alkylene glycol or a polymer thereof. Alkylene glycol is said to act as a vehicle to help limit dehydration of skin and improve sensory feel of product. There is no teaching or suggestion of combining with long chain a-hydroxy acid esters or that by doing so dehydration effect can be ameliorated.
U.S. Pat. No. 5,002,680 to Schmidt et al. teaches mild skin cleansing aerosol mousse compositions with skin feel and moisturization benefits. Among the moisturizers which can be used are taught non-occlusive moisturizers (including lactic acid esters) and occlusive moisturizers (e.g., petrolatum, mineral oil) in formulations comprising surfactant, polymeric skin feel aid and propellant. The lactic acid esters are taught generally, but there is no teaching or suggesting of mixing long chain and short chain .alpha.-hydroxy acid esters or any teaching or suggestion that one (short term benefit of long chain esters) may complement the possible deficiencies (i.e., short chain esters may be drying in the short term even though providing longer term benefit) of the other.
U.S. Pat. No. 4,529,605 to Lynch teaches a bathing oil composition comprising a nonionic surfactant, a cationic surfactant and a primary emollient which may be a long chain lactate ester. There is no teaching of short chain esters or of combinations of long and short chain esters.
U.S. Pat. No. 4,234,599 to Van Scott et al. relates to a method of treating dry skin by topically applying a composition (e.g., cream, ointment) containing alpha or beta hydroxy acids or esters thereof. Specific mixtures of long and short chain .alpha.-hydroxy acid are neither taught nor suggested.
In "A Study to Assess the Moisturizing Keratolytic Antiacne and Antiaging Effect of Alpha-Alpha-Hydroxy acid Esters" by L. Celleno, A. Vasseli, M V. Tolaini, G. Serafina, G, Ferte, C. Gemona (In Cosmetics' Exhibition & Conference, Paris, France, Apr. 5-7, 1995), the beneficial effects of various alpha-hydroxy esters is taught. Again, however, there is no teaching or suggestion of using short chain and long chain esters in the same composition.
In International Publication WO 95/05160 (assigned to Unilever), there is taught cleanser formulation containing esters of hydroxy alkanoic acid as conditioners. There is no teaching or suggestion of using mixtures of short and long chain .alpha.-hydroxy acid esters or that the two should be simultaneously used to provide dual benefits.
It is thus one object of the invention to provide a unique composition which provides the long term moisturizing benefits provided by short chain length .alpha.-hydroxy acids while at the same time masking the short term dryness often caused by the short chain esters by using long chain esters of .alpha.-hydroxy acids to provide short term moisturizing benefits.